1. Field of the Invention
The present invention relates to an exhaust gas sampling device for an outboard motor.
2. Description of the Prior Art
In order to analyze noxious components contained in exhaust gas discharged from an engine of an outboard motor, it is a conventional practice to sample the exhaust gas from an exhaust gas sampling pipe mounted in an exhaust passage and analyze the exhaust gas by a component measuring instrument. There is such a conventionally known exhaust gas sampling device for an outboard motor, which is described in Japanese Patent Application Laid-open No.166495/92.
An exhaust gas sampling pipe in the above prior art exhaust gas sampling device is threadedly inserted into an exhaust pipe and fixed thereto by means of a lock nut, and an opening in the exhaust gas sampling pipe which extends through an outer wall of the outboard motor and which is exposed to the outside, is occluded by a plug. In sampling the exhaust gas, the plug is removed, and the exhaust gas component measuring instrument is connected to the pipe.
In the above prior art exhaust gas sampling device for the outboard motor, however, a tip end of the exhaust gas sampling pipe is exposed to the outside from the outer wall of the outboard motor. Therefore, if the sampling pipe is formed of a material not resistant to rust and corrosion when seawater splashes on the exhaust gas sampling pipe, a rust or corrosion is generated, which causes problems of reduction in durability of the exhaust gas sampling pipe, an inconvenience in the operation of removal of the plug, and a degradation of appearance. The outside plug, further, causes a possibility that the exhaust gas sampling pipe may be damaged by hitching on another object during transportation of the outboard motor or, for example.